1. Field of the Invention
The present invention pertains generally to automobile drive systems and, more particularly, to vehicle assemblies that are adapted to permit movement or travel of the engine and other structural components in the event of a front-end collision.
2. Description of Related Art
When a vehicle is involved in a front-end collision, it is important that the engine and other structural components of the vehicle be permitted sufficient space to crush or otherwise move and help absorb the kinetic energy of the crash. In the most severe crashes, the crush space is insufficient and components of the vehicle engine and structural assembly may be forced into the passenger compartment.
While crumple zones in the body panels and frame are constructed to provide a desired impact-absorption, the overall ability of the vehicle to absorb the load of front-end collisions has always been limited by the drive train, especially in vehicles having driven rear-wheels (i.e., either rear wheel or four wheel drive vehicles). This limitation is due, in part, to the rigid connection existing between the engine and the rear drive shaft, which is embodied by the propeller shaft.
The propeller shaft can be of one piece or two-piece construction. In either case, a center of the propeller shaft is typically guided by a center support to prevent sagging. A conventional two-piece propeller shaft and center support is taught by U.S. Pat. No. 4,732,230, the disclosure of which is expressly incorporated herein in its entirety. The center support normally includes a resilient casing that is surrounded by a U-shaped bracket. The casing and bracket cooperate to support the weight of the shaft and, in the case of two-piece propeller shafts, is adjacent the joint or connection between the two propeller pieces. Unfortunately, in front-end collisions, the center support is also the location at which the propeller shaft jams against the under-surface of the vehicle, thereby limiting the rearward stroke of the engine.
The conventional solution to this problem has been to manufacture the propeller shaft so that it breaks when involved in a crash. However, due to the many types of crashes, each with different severity and load, this solution has been found to not be empirically reliable, and may lead to inconsistent results. Therefore, there exists a need in the art for a method and device for facilitating rearward movement of the propeller shaft relative to the center support in the event of a front-end collision. There also exists a need in the art for a device and method to increase the crash stroke of the engine during a front-end collision.
The present invention is directed toward a device that guides the propeller shaft rearwardly in the event of a front-end collision, and helps to prevent jamming of the propeller shaft. The present invention is further directed toward a device that effectively increases the vehicle crash stroke and absorption of energy by the vehicle in the event of a front-end collision.
In accordance with one aspect of the present invention, an improved central support structure for a vehicle propeller shaft is provided. The central support structure is disposed at a predetermined position along the length of the propeller shaft and is adapted to support the propeller shaft vertically relative to a lower surface of the vehicle. The support structure permits and facilitates movement of the propeller shaft rearwardly during a front-end collision between the vehicle and another object.
In further accordance with the present invention, the central support structure includes a support bracket, a resilient annular support, and a deflector. The support bracket is secured to a lower surface of the vehicle at a predetermined position and surrounds at least a lower portion of the propeller shaft. The resilient annular support substantially surrounds the propeller shaft at the predetermined position and is supported by the support bracket. The deflector is secured to the lower surface of the vehicle adjacent the predetermined position. The deflector is sized and positioned so as to guide the propeller shaft through the support bracket during a front-end collision.
In further accordance with the present invention, the deflector includes a curved surface that faces toward the propeller shaft. During a front-end collision, the curved surface is engaged by the propeller shaft and directs the propeller shaft through the support bracket.
In further accordance with the present invention, the propeller shaft has a longitudinal axis and a rotational direction. At least a portion of the deflector is disposed at a position relatively forward of the predetermined position and offset from the longitudinal axis in the rotational direction.